This is actually my first hybrid, which I was planning to build for the SF-contest, but when i got tired waiting for the contest to start I decided to give the other contestants a chance and just build it out of contest. I got the idea when i was talking with DYI about what record i would try to break. I was first thinking a 40-50x hybrid, but when DYI proposed that I should build a hybrid using over 100x I couldn't resist the challenge.This gun is designed to withstand mixes up to and even over 200x Air-Propane and is made out of EN 1.4462 high strength stainless steel. http://hv4all.com/hybrid/EN1_4462-0509.pdfIt's machined out off a solid 60mm bar and has a chamber volume of just over 100cc. Here is a early render and drawing of the chamber, i made changes i some dimensions and other details, but it still gives a good picture of how its designed.http://hv4all.com/hybrid/chamber.PDFBecause of the high pre-ignition pressure i cant use a normal spark gap, instead i use a thin wire that is connected to a relatively low voltage power source witch makes it possible to ignite the fuel-air mixture .

The chamber and its parts, including the custom made wrench i made.

To reduce the recoil i machined a mount for the chamber and built a recoil absorber of some gas springs and other parts i had laying around.

I use a 5000PSI gauge to measure the pressure of both fuel and air in the chamber, its calibrated to better then +-0.1% of reading at 20-100% of full scale and +-0.02% of full scale at 0-20% of full scale.I have tested it at low mixes and it works flawless even low as 5x.Calibration test results

I first tested the cannon with oxy-propane up to 40x and then with air-propane up to 190x.When i used oxy-propane i tried to replace all the air in the chamber with oxygen before adding the fuel to increase the power, but instead of that i got a really bad shoot and i am almost certain that i got DDT.Because when i recovered the steel projectile i noticed that a piece of the brass burst disk had embedded itself almost a half mm into the back of the projectile.Even at 190x with air-propane i haven't got this problem , so i think its the Nitrogen in the air that's prevent DDT from happening

Now Larda, I've been complimenting your work on this cannon since you first bored the chamber out of a big hunk of steel a few months ago, and I have to say once again, it's really an amazing piece of work. Of all the crazy ideas I've ever suggested to people with machining facilities, this is the first that's been built. And what a build!

In this case, I can't really make my standard post asking about all the exact specifications and capabilities, because I know them almost as well as you do yourself. Once again, congratulations. This is truly a momentous day in the world of spudding, and I'm sure it'll be remembered for quite a while here. Here's hoping that not too many people get themselves killed trying to beat these records

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Spudfiles' resident expert on all things that sail through the air at improbable speeds, trailing an incandescent wake of ionized air, dissociated polymers and metal oxides.